1. Field of the Invention
The present invention relates to an apparatus and a method for recording/reproducing a digital signal such as a digitized video signal, and in particular to a helical scan type digital VCR capable of reproducing recorded data at a reproduction speed different from the normal reproduction speed and a recording/reproducing method using the VCR.
2. Description of the Related Art
A conventional technique for reproducing data at a variable-speed by using a digital VCR is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2-94071.
According to this conventional technique, a video signal is recorded on tracks provided on a magnetic tape by using a magnetic head. The track on the magnetic tape has sub-code areas located along the paths of scanning by the magnetic head during a variable-speed reproduction, and still frame data extracted from the video signal is distributively recorded in the sub-code areas over a plurality of tracks. In variable-speed reproduction, the still frame data is obtained by reproducing the data recorded in the sub-code area, thereby displaying a picture. In order to prevent the magnetic head from scanning off the paths on the distributively located sub-code areas, tracks to be scanned are selected, and the phase of the magnetic tape and the magnetic head is controlled by using a capstan motor.
However, in such a conventional variable-speed reproduction apparatus using sub-code areas, the variable reproduction speed allowing still frame data to be stably obtained is limited to one kind of speed. Recently, limitation to only one kind of variable reproduction speed for VCRs has been inefficient, and the demand for VCRs having a plurality of variable reproduction speeds has been increased. In order to reproduce data at a plurality of variable reproduction speeds by using the conventional technique, it is required to locate the data on each path scanned by the head at different variable reproduction speeds. This makes the data format on the magnetic tape complicated, as well as decreasing the efficiency in using a recording medium because of recording waste data.
Since a picture reproduced at a variable-speed is displayed as a series of intermittent still pictures, in order to update the displayed picture, all the data for one still frame have to be reproduced from a plurality of sub-code areas. Because the sub-code areas being distributively located over a plurality of tracks, when all the data for one still frame have been reproduced from the sub-code area for a variable-speed reproduction, data for normal-speed reproduction corresponding to the still frame data exists at a position far away from the track in which this sub-code area is recorded. Accordingly, there is a problem of an increasing amount of excessive scanning in variable-speed reproduction.